


Combustion

by noyabeans (snowdrops)



Series: writing with snowdrops (zine collection) [4]
Category: Haikyuu!!
Genre: Canon Compliant, Enemies to Friends to Lovers, M/M
Language: English
Status: Completed
Published: 2020-01-10
Updated: 2020-01-10
Packaged: 2021-02-27 05:40:45
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 774
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22191955
Author URL: https://archiveofourown.org/users/snowdrops/pseuds/noyabeans
Summary: COMBUSTION:Aclass of exothermic reaction in which a compound reacts with an oxidant to produce heat and a new product, commonly known as burning.Sample equation:Kuroo Tetsurou + Yaku Morisuke→______
Relationships: Kuroo Tetsurou/Yaku Morisuke
Series: writing with snowdrops (zine collection) [4]
Series URL: https://archiveofourown.org/series/1597471
Comments: 6
Kudos: 148





	Combustion

**Author's Note:**

> **In celebration of Haikyuu Season 4!**

_**COMBUSTION:**  
_ _A_ _class of exothermic reaction in which a compound reacts with an oxidant to produce heat and a new product, commonly known as burning._

Sample equation:  
_Kuroo Tetsurou + Yaku Morisuke_ → ________

The first time he met Yaku Morisuke on the last day of their first week of high school, Kuroo Tetsurou thought he had the answer:

 _Kuroo Tetsurou + Yaku Morisuke_ → _Rivals_

Somewhere near the end of first year, he was eating dinner with Yaku and Kai after training. He and Yaku had settled into an awkward truce, no longer at permanent odds with each other, but also nowhere close to being _friends_. Kai, naturally, was an inert gas, always neutral even when sandwiched between them.

Kuroo was halfway through a mouthful of noodles when Yaku, who had slid out of his seat muttering about water, precariously balanced three full glasses back to their table and placed one of them in front of Kuroo without any comment.

There was no scientific instrument to reliably measure it, but assuming the reactants were Yaku’s hostility towards him and vice versa, he figured the eight months from last April to now might be their half-life — the time taken for the concentration of a reactant to reduce by half.

“Yaku, here’s to our half-life,” he said, raising his glass without thinking twice, meeting with two very confused pairs of eyes, one of whose eyebrows began twitching a few seconds later.

“Are you saying I have a short life? It sure doesn’t pay to be nice to you, huh?”

 _Kuroo Tetsurou + Yaku Morisuke_ → _…Friends?_

Second year saw Yaku find him sitting alone in the middle of the gymnasium early one morning. The seniors had just stepped down, citing their loss at qualifiers and prioritizing their entrance exams. In their absence, Kuroo had found himself as substitute captain.

Of course he had spoken with Kai and Yaku before; captaincy was something he had known he would shoulder at some point, but to do so a full half-year earlier than he had expected, with the weight of their defeat to Yukigaya High on his back — Kuroo was, to put it lightly, feeling the heat.

“I don’t know how to get my desired products out of a reaction I’m not sure I can control,” he murmured, looking out across the emptiness of the court. Sure, certain chemical reactions could be directed by force, but that was not the leader he wanted to be. “Kenma and Yamamoto are doing their best, but next year we’ll have new juniors. There’s so much we can’t predict —”

Yaku sat down next to him, reaching over to pull Kuroo’s shoelaces loose. “Are you seriously such a nerd that you think of your team in chemical terms? People aren’t as predictable as chemical compounds, you know. It’s called experimentation. You never know what you can get until you’ve gotten it, and you keep trying until you get it. Shouldn’t you know this better than any of us,” a pause, “ _captain_?”

 _Kuroo Tetsurou + Yaku Morisuke_ → _Teammates_

Theoretically, endorphins and adrenaline are chemicals that don’t react with each other. But when he pulls Yaku in for a hug, he has nothing to blame it on but the collision between the endorphins and adrenaline coursing through his system.

 _We did it_ , he thinks, a little dazed, a little stunned, grounded by the weight of Yaku’s body against his own. _We made it to Nationals._ Yaku’s beaming, his eyes bright and shining in a way Kuroo has never seen before. He feels a little more breathless looking at Yaku like this, so he looks away for fear of his heart well and truly combusting from sheer joy.

 _Kuroo Tetsurou + Yaku Morisuke_ → _??_

In chemistry, interactions between two or more compounds result in a reaction, leaving one or both changed. And since humans are made of chemicals, Kuroo figures the same rules apply to people too, even if Yaku begs to differ.

Docosahexaenoic acid, astaxanthin, what have you — in the last three years, Yaku has become as familiar to him as any chemical compound. The way he scowls when Lev accidentally insults his height, the way he winces when biting into a red hot chili. The way he grins, the way he laughs, the way he smiles, the way he flushes when he’s embarrassed, the way his fingers thread into Kuroo’s own like it’s second nature. Kuroo has carefully filed away all of his reactions in his mental notes, treasuring each and every one.

And although Kenma cringes and Yaku backs away whenever he so much as mentions it, Kuroo thinks the best chemical reaction he’s ever discovered is:

 _Kuroo Tetsurou + Yaku Morisuke_ → _Happiness_

**Author's Note:**

> My first piece for the [Haikyuu Symbolism/This Is Also Volleyball zine](https://twitter.com/HaikyuuSymbols), kindly betaed by [nachuuki](https://archiveofourown.org/users/nachuuki/pseuds/nachuuki). 
> 
> [tumblr (rielity)](https://rielity.tumblr.com/) | [twitter (noyabeans)](https://twitter.com/noyabeans) | [haikyuu writing journal](https://noyabeans.dreamwidth.org/)


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